Route searching apparatus and route searching method

ABSTRACT

A route searching apparatus includes a travel route accumulation unit, an algorithm selection unit to select route searching algorithms to meet the preference of a user based on the accumulated travel routes, and a route searching unit to perform a route search up to a destination by using the selected algorithms. Preferably, the algorithm searching unit searches for each of the travel routes accumulated in the accumulation unit by means of several algorithms, calculates, for each algorithm, a match rate between the searched route and the actual travel route, and selects an algorithm of the highest match rate. Also, it is preferable that a condition common to roads avoided by the user is extracted from the accumulated travel routes, and a route search is performed by adjusting search costs so as to make such roads less prone to be selected.

TECHNICAL FIELD

The present invention relates to a route search technique for searchingfor a route to a destination, and more particularly, it relates to sucha technique that performs a route search by using a route searchingalgorithm to meet user's preference.

BACKGROUND ART

In the past, there have been widely used route searching apparatuses(navigation apparatuses) that enables driving on an unfamiliar road in asmooth manner. In the route searching, there exist a plurality of routesearching algorithms such as, for example, a shortest travel routealgorithm, a shortest travel time algorithm, a toll road priorityalgorithm, an algorithm of using no toll road, etc. Accordingly, thereare adopted the following techniques. That is, route searching isperformed after a user is required to designate a route searchingalgorithm beforehand, or route searching is performed by using aplurality of algorithms, and a plurality of searched routes arepresented to a user.

Further, to perform route selection so as to more meet user'spreference, the following techniques have been proposed. In a firstpatent document, there is proposed a technique in which a routecalculated based on map data is compared with traveled route data, andsearch costs are modified based on the result of the comparison tocalculate a route to a destination. In addition, in a second patentdocument, a technique is proposed in which routes and junction orbifurcation points are obtained according to a plurality of searchconditions, and a user is required to set his or her favorite guidanceroute.

CITATION LIST Patent Literature

-   PTL 1: Japanese patent No. 3596704-   PTL 2: Japanese patent application laid-open No. 2007-240400

SUMMARY OF INVENTION

However, there are the following problems in the above-mentioned priorart. In general, the user's tendency (preference) of route selectiondoes not necessarily meet a predefined route searching algorithm.Accordingly, even if a user is intended to search for a route to meethis or her favor from among the results of searches made according to aplurality of route searching algorithms, it is difficult for the user todetermine which route is suitable for his or her purpose in an unknownor unfamiliar place.

The technique described in the first patent document operateseffectively only in known or familiar places since the search costs ofroutes different from actual traveled routes (traveled path data) aremodified. In addition, the technique of the second patent documentrequires user's own operation of selecting a guide route at eachjunction or bifurcation point, and hence is troublesome.

The present invention has been made in view of the above-mentionedcircumstances, and has for its object to present a route that meets auser's preference even in a place where the user has not traveledbefore.

In order to achieve the above-mentioned object, route searching iscarried out according to the following units or processing.

A route searching apparatus according to the present invention iscapable of using a plurality of route searching algorithms, and includesa travel route accumulation unit that acquires and accumulates routeswhich have been traveled, an algorithm selection unit that selects aroute searching algorithm to meet preference of a user based on theaccumulated travel routes, and a route searching unit that performs aroute search up to a destination by using the selected algorithms.

Here, the algorithm selection unit first searches for a route leadingfrom a starting point to a destination point of each of the accumulatedtravel routes by using the plurality of algorithms, respectively. Then,it calculates, for each algorithm, a match rate (a route match rate)between the route obtained as a result of the search and an actualtravel route. Thereafter, it calculates, for each algorithm, a matchrate between a route selection tendency of the user and the algorithm (apreference degree of the algorithm). This match rate between the routeselection tendency of the user and the algorithm can be calculated foreach route based on the route match rate thereof. For example, it ispreferable to obtain the match rate of the algorithm by averaging theroute match rates of the respective accumulated routes (this can alsodone by weighted averaging). Then, the algorithm selection unit selects,as an algorithm to meet the preference of the user, an algorithm ofwhich match rate with respect to the route selection tendency of theuser is the highest.

Thus, by determining the user's preference to route selection from thepast travel routes of the user, it becomes possible to present a routesuitable for the user even in an unfamiliar place.

In addition, preferably, the algorithm selection unit in the presentinvention seeks mismatch points that are points at which the routeobtained as a result of the search and the actual travel route branchfrom each other, and performs, when there exists a mismatch point, a newroute search from the mismatch point onward, and calculates the routematch rate by making use of this search result, too.

In this regard, for example, when a route resulting from a search and anactual route are different from each other in a point near from thestarting point, all paths in the remainder of the entire range becomedifferent, but this does not necessarily mean that the user does notlike the route searching algorithm. Accordingly, by performing a newroute search from the mismatch point onward thereby to obtain the matchrate of a new route with respect to the actual route, it becomespossible to make a more accurate determination as to whether the userlikes the route searching algorithm.

Moreover, the algorithm selection unit in the present invention canextract a common point (mismatch common point) for a plurality ofmismatch points obtained from a plurality of search results. Then, whenperforming a route search by means of the selected algorithms, the routesearching unit preferably performs the route search by making larger theselection cost for a link matching the mismatch common point (making thelink less prone to be selected). Here, note that as common points orfeatures, there are listed, for example, traffic information (thepresence or absence of a traffic signal, the presence or absence ofcongestion, one-way traffic, etc.), surrounding POI (Point of Interest)information, (facilities such as shops, schools, etc.), and so on.

If, for many routes, there exist links (types of links) that aredifferent from the search results thereof, a determination can be madethat such routes do not meet the preference of the user. Accordingly, byseeking a common mismatch point and making larger the selection cost insuch a link, it is possible to perform route selection that more meetsthe user's preference.

Here, note that in case where a mismatch common point is used as statedabove, preferably, the route searching unit makes a search by using theselected algorithms, and when there exists a link matching the commonpoint on the search route, performs a route search again after settingthe cost of the link larger.

To modify the costs for mismatch common points in all the links up tothe destination increases processing load, and hence a route search isfirst made without taking account of any mismatch common point, and onlywhen there is a mismatch common point on a searched route, costmodification is carried out, whereby it becomes possible to perform theprocessing in an efficient manner.

Here, note that by limiting the execution of route re-searching to thetime when there exists no avoidance point on the route obtained as aresult of the search, or the time when the same route is selected, itbecomes possible to obtain a route that meets the preference of theuser. However, an upper limit can be set for the frequency of researchin consideration of the processing time.

Here, note that the present invention can be caught as a route searchingapparatus that has at least part of the above-mentioned units. Inaddition, the present invention can be understood as a route searchingmethod including at least part of the above-mentioned processing or aprogram to achieve such a method. The above-mentioned individual unitsand processing of the present invention can be arbitrarily combined withone another in any possible way to constitute the invention.

According to the present invention, even in a place where a user has notyet traveled before, it becomes possible to present a route that meetsthe preference of the user.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing the functional construction of a car navigationapparatus according to a first embodiment of the present invention.

FIGS. 2A through 2D are views showing the construction of a travelhistory table, a route table, an OD table, and a POI table,respectively.

FIG. 3 is a flow chart illustrating the flow of algorithm preferencedegree calculation processing.

FIG. 4A is a view explaining mismatch points in a route search, and FIG.4B is a view explaining re-searching processing at the time when thereexist such mismatch points.

FIG. 5 is a view showing the construction of a route match rate table.

FIG. 6 is a view showing the construction of an algorithm preferencedegree table.

FIG. 7 is a flow chart illustrating the flow of route searchingprocessing.

FIG. 8 is a view showing the functional construction of a car navigationapparatus according to a second embodiment of the present invention.

FIG. 9 is a view showing the construction of a mismatch point table.

FIG. 10 is a flow chart illustrating the flow of the processing ofextracting avoidance points, which is a common condition to mismatchpoints.

FIG. 11 is a view showing the construction of an avoidance point table.

FIG. 12 is a flow chart illustrating the flow of route searchingprocessing.

DESCRIPTION OF EMBODIMENTS

Now, preferred embodiments of the present invention will be describedbelow in detail by way of example while referring to the accompanyingdrawings.

First Embodiment

A car navigation apparatus according to this embodiment determines whatroute selection a user likes by analyzing routes on which the user hasthus far traveled, and in case where a route search is freshlyperformed, a route searching algorithm to meet a user's preference isused. FIG. 1 is a schematic view showing the functional construction ofa car navigation apparatus (route searching apparatus) according to thispresent invention.

This car navigation apparatus is substantially provided with a travelroute accumulation part 3, an algorithm selection part 5, and a routesearching part 6, wherein the algorithm selection part 5 serves toselect a route searching algorithm to meet the preference of a user byanalyzing the travel routes accumulated by the travel route accumulationpart 3, and the route searching part 6 performs a route search by usingthe algorithm thus selected.

Here, note that as examples of such a route searching algorithm, thereare enumerated a shortest distance (distance priority) algorithm, aminimum time (time priority) algorithm, a toll road priority algorithm,a right turn avoidance algorithm, etc., but the present invention is notlimited to these algorithms, and any arbitrary route searching algorithmcan be used.

<Route Accumulation Processing>

The travel route accumulation part 3 obtains a travel route (travellink) and stores it in a travel history table 4 by matching positiondata acquired from a GPS device 1 and map data 2 containing linkinformation. In this embodiment, a searching algorithm to meet thepreference of each user is obtained, so it is desirable to store thehistory data of the travel route for each user. For such a purpose, itis preferable to identify the user at the time when the user operatesthe apparatus.

A specific construction of the travel history table 4 is shown in FIGS.2A through 2D. As shown in FIG. 2A, the travel history table 4 has aroute set ID 411 for each combination of a user ID 412, an OD(Origin/Destination: a start point/an end point)-ID 413, a route ID 414,and stores therein its travel frequency 415 and the last update date 416thereof.

A route table (FIG. 2B), an OD table (FIG. 2C), and a POI (Point ofInterest) table (FIG. 2D) are used as other tables for assisting thetravel history table 4.

The route table stores therein route IDs 421, OD-IDs 422, and linkseries 423. A link series 423 is that IDs of links constituting a routeare arranged in order of the route. As can be seen from the figure, incase where routes are different from each other even if start points andend points thereof are the same, respectively, these routes are storedas records having different route IDs. The OD table stores therein ODdata, i.e., OD-IDs 431, start points (origins) 432 and end points(destinations) 433. For the start points and the end points, theirpositions are stored as POI-IDs. The POI table stores therein POI data,i.e., POI-IDs 441, latitudes 442, longitudes 443, and places 444.

<Algorithm Selection Processing>

The algorithm selection part 5 obtains a route searching algorithm tomeet the preference of a user from the travel history table 4 that hasbeen prepared by the travel route accumulation part 3. The algorithmselection part 5 substantially has a route match rate calculation part51, and an algorithm preference degree calculation part 56. The routematch rate calculation part 51 calculates to what extent a route (aroute stored in the route table) actually traveled by the user and aroute search result obtained according to each searching algorithm matchwith each other, and stores the results obtained in a match rate table55. The algorithm preference degree calculation part 56 calculates, froma travel history of routes traveled by each user in the past and theroute match rate table 55, an algorithm preference degree that indicatesa tendency of which route selection algorithm is favored by each user,and stores it into an algorithm preference degree table 57.

More specifically, the route match rate calculation part 51 in thealgorithm selection part 5 is provided with a route searching part 52, amismatch point extraction part 53, and a route match rate calculationpart 54. A detail of the operations of the respective functional partswill be explained below together with a flow chart illustrated in FIG.3. FIG. 3 is the flow chart illustrating the overall flow of algorithmpreference degree calculation processing performed by the algorithmselection part 5.

The route searching part 52 searches, for each of the routes stored inthe travel history table 4, a route from its start point (origin) to itsend point (destination) according to predefined route searchingalgorithms. Specifically, in step 31, an start point and an end point ofa route stored in the travel history table 4 are first input as adestination condition for route searching. Then, in step S32, one of thepredefined route searching algorithms is selected, and in step S33, aroute search is executed by using the algorithm thus selected.

In step S34, the mismatch point extraction part 53 extracts mismatchpoints between an actual travel route and a route obtained as the resultof the search. For example, as shown in FIG. 4A, in case where a linkseries of the actual travel route is 1, 2, 3, 4 and 5 and a link seriesof the travel route obtained as the search result is 1, 6, 7 and 8, itis judged or determined that a mismatch has occurred at a node N1. Inthis case, the route searching part 52 returns to step S33, where itperforms a route search again by setting, as a start point, a node N2that is a terminal node of a link (i.e., link 2) on which the mismatchhas occurred. This re-searching processing is assumed to be continuouslyperformed as long as there is a mismatch in the search result thereof.In an example of FIG. 4B, a link series of a route as a result of thesearch becomes to be 1, 6, 3, 4 and 5. Here, note that link 6 and link 3are not connected to each other, but the purpose is to obtain the matchrate of the searched route, so there is no problem in such a result. Inaddition, by performing re-searching as stated above, it is possible toreflect the user's actual travel history as much as possible whencalculating to what extent the tendency of user's route selection andthe route searching algorithm meet with each other.

Then, in step S35, the route match rate calculation part 54 calculates amatch rate between a route actually traveled by the user and a route forwhich a search has been made according to a certain route searchingalgorithm, and stores it in the route match rate table 55. The matchrate of a route is a value that denotes to what extent the user's actualtravel route and the route searched according to the certain routesearching algorithm match with each other. The match rate of a route canbe obtained, for example, as (the number of matched links)/(the numberof links of an actual travel route), or (the total distance of matchedlinks)/(the total amount distance of an actual travel route). Inaddition, the match rate of a route can also be obtained as (the numberof matched nodes)/(the number of nodes of an actual travel route), or itcan be obtained as (the number of matched nodes)/(the number of nodes ofan actual travel route) with respect only to nodes that connect links ofdifferent kinds of roads to one another.

The calculation of a route match rate is performed according to all thepredefined route searching algorithms for each route. Accordingly, instep S36, it is determined whether match rates have been calculated withthe use of all the algorithms, and when there is any algorithm by meansof which a match rate has not yet been calculated, a return is made tostep S32 where the match rate for that algorithm is calculated.

On the other hand, when the match rates of a certain route have beencalculated according to all the algorithms (S36: YES), it is thendetermined in step S37 whether there exists any route for which matchrates have not yet been obtained, and when there exists an unprocessedor unfinished route in the travel route or history table 4, a return ismade to step S31 where the match rates of that route are calculated.

The match rates obtained in the above-mentioned manner is stored in theroute match rate table 55. An example of the route match rate table 55is shown in FIG. 5. The route match rate table 55 stores therein searchIDs 551, route IDs 552, OD-IDs 553, searching algorithms 554, linkseries 555, and match rates 556. As shown in this figure, a match rate556 between a searched route (link series 555) and the actual travelroute (route ID 552) is stored for each searching algorithm 554, foreach route.

When the match rate of a searched route according to each searchingalgorithm have been obtained for each route, the algorithm preferencedegree calculation part 56 calculates the algorithm preference degree ofeach algorithm which is a degree at which the user's route searchingtendency and the route searching algorithm match with each other, andstores it into the algorithm preference degree table 57. The algorithmpreference degree of a certain searching algorithm is calculated basedon match rates between respective routes actually traveled by a user andsearch results according to the searching algorithm to be examined. Forexample, it can be obtained by taking an average of the match rates forthe respective routes actually traveled by the user which are weightedaccording to the frequency or number of travels of each route. Thisweighting can be a value that becomes larger in proportion to the travelfrequency. However, in order to prevent the route selection tendency tothose routes which are frequently traveled by the user from beingexcessively reflected, it is preferable to make use of weighting thatincreases in accordance with the travel frequency but with the rate ofincrease being gradually decreased. In addition, in order to have arecent route selection tendency reflected more, it is also preferable todecrease the weighting with the increasing lapse of time from the lastupdate date.

FIG. 6 shows an example of algorithm preference degree table 57. Thetable stores therein user IDs 571, searching algorithms 572, and matchrates (preference degrees) 573, as shown in FIG. 6. In this manner, thematch rate of each searching algorithm with respect to the routesearching tendency of each user, i.e., the preference degree of thesearching algorithm of each user, is stored in the algorithm preferencedegree table.

Here, note that at an appropriate time such as when a user stops adriving operation (i.e., at the time of turning off the engine), or whena user starts a driving operating (i.e., at the time of starting up theengine), the above-mentioned calculation processing of the algorithmpreference degree according to the algorithm selection part 5 need onlybe carried out for a travel history till then. In this regard, there isno need to perform the above-mentioned processing for all the routesevery time, but instead the above-mentioned processing need only becarried out for those routes which have been newly added from the lastexecution thereof. In addition, a travel route of a user might contain arelay or intermediate point (stopover point) while the user travels froman operation start position up to an operation end position, and hencethe processing can be done after asking for user's confirmation as towhether there is any relay point. Moreover, although in the abovedescription, it is explained that match rates are obtained for all thetravel routes, a part of the travel routes can be excluded from thematch rate calculation processing.

<Route Searching Processing>

When a starting point (ordinarily, a point of the current position) anda destination point are provided by a user, the route searching part 6searches for a route to its destination. When this route search isperformed, route selection is carried out by using the most suitablealgorithm that meets the preference of the user, by referring to thealgorithm preference degree table 57.

FIG. 7 is a flow chart illustrating the flow of the route searchingprocessing. First of all, the route searching part 6 receives an inputof a destination from a user (step S71). Here, the current positionobtained from the GPS device 1 is used as the origin of a route search.Then, a route selection algorithm to most meet the route selectionpreference of the user is selected by referring to the algorithmpreference degree table 57 (step S72). Thereafter, the route searchingpart 6 performs a search for a route by using the thus selected routesearching algorithm (step S73), and presents the result of the search tothe user by displaying it on a display device or the like (step S74).

<Effects of this Embodiment>

According to this embodiment, it is possible to determine, from thehistory of the routes thus far traveled by a user, a route selectionalgorithm that most meets or matches the preference of route selectionof the user. Accordingly, it becomes possible to present a routesearched by the route selection algorithm most matched to the user'spreference at the time when a route search is freshly carried out.

According to such a method, even in a place where a user has not yettraveled and is unfamiliar, it becomes possible to search for a routethat resembles the routes that the user uses in daily life and topresent it to the user.

Conventionally, only a few kinds of route searching algorithms have beenused, because an increase of algorithms makes it difficult for a user todecide which algorithm to choose. According to this embodiment, however,even in the case of using a multitude of searching algorithms, it is notnecessary for a user to explicitly designate which searching algorithmto use. Accordingly, it becomes possible to select, from among themultitude of searching algorithms, the most suitable one to meet theuser's preference without placing a burden on the user.

Second Embodiment

A car navigation apparatus according to a second embodiment of thepresent invention, in addition to having the functions of the firstembodiment, extracts points (links) which a user avoids travelingthrough, and makes it more difficult to select a route including suchpoints, thereby presenting a route that more meets the route searchingtendency of the user.

FIG. 8 shows the functional construction of a car navigation apparatusaccording to the second embodiment of the present invention. What isdifferent from the first embodiment is that provision is made for amismatch point table 7, an avoidance point extraction part 8, and anavoidance point table 9.

<Avoidance Point Extraction Processing>

In case where there are mismatch points in an actual travel route and asearch result route in the route match rate calculation part 51, themismatch points are stored in the mismatch point table 7. The mismatchpoint table 7 stores therein user IDs 701 and mismatch link pairs 702,as shown in FIG. 9. A mismatch link pair is a pair of links for which amismatch is generated, and in case where a link 2 has actually beentraveled at node N1 but a searching algorithm selects link 6, as shownin FIG. 4A, a mismatch link pair becomes to be 2 and 6. Mismatch pointsare information specific to each user, so they are stored for each userID.

In FIG. 9, a link pair in which a mismatch has been generated is merelystored, but the frequency of mismatches generated for that link pair andthe frequency of times when a route selected according to a searchingalgorithm and an actual travel route have matched with each other can bestored respectively. That is, the ratio (probability) of occurrence ofmismatches can be stored. This is because for a certain link pair, amismatch is not generated every time, and in many cases, when a linkselected by a searching algorithm is traveled, the user does notnecessarily avoid that link. Thus, by storing the ratio at which thelink is avoided, it becomes possible to determine the link avoided bythe user in a more adequate manner.

The avoidance point extraction part 8 extracts from mismatch point table7 the links (avoidance points) which are avoided by the user. Theextraction of the avoidance points is executed by obtaining commonpoints that exist in the mismatch points contained in the mismatch pointtable 7. For example, some conditions (for example, congestion, rightturn, school plant, etc.) that are considered as reasons for mismatchesare established, and it is determined whether each mismatch pointcontained in the mismatch point table meets these conditions. When apredefined condition appear as a mismatch point more than apredetermined number of times, it can be determined that the user avoidsthe point of such a condition. In addition to that, it is possible toextract avoidance points by using the technique of neural network, etc.,too.

FIG. 10 illustrates, as a flow chart, one example of the flow ofavoidance point extraction processing that is carried out by theavoidance point extraction part 8. In this example, the avoidance pointextraction part 8 beforehand holds the reasons (mismatch conditions)that are considered as reasons for those points which are avoided byusers. For example, school routes, traffic signals, right turns,congestions, etc., can be listed as mismatch conditions.

The avoidance point extraction part 8 extracts mismatch points from themismatch point table 7 (step S101). Then, it is determined whether themismatch points thus extracted meet the mismatch conditions beforehandheld in the avoidance point extraction part (step S102). For example, incase where a link selected by using a searching algorithm is a schoolroute and a link actually traveled by a user is not a school route, amismatch condition “school route” will be met. In this case, a countvalue for the mismatch condition thus met is incremented (step S103).Here, note that one mismatch point might meet a plurality of mismatchconditions. The counting of such mismatch conditions is performed forall the mismatch points (step S104).

Subsequently, when the count value for a mismatch condition becomesequal to or more than a predetermined value, a link having such acondition is extracted as an avoidance point, and is stored into theavoidance point table 9 (step S105). For example, if the count value forthe mismatch condition “school route” is equal to or more than thethreshold value, a determination can be made that the user tends toavoid school routes, and hence school routes are extracted as avoidancepoints.

The construction of the avoidance point table 9 is shown in FIG. 11. Theavoidance point table 9 includes user IDs 901 and avoidance points 902,and stores therein, for each user, what kinds of points the user avoids.

<Route Selection Processing>

Next, reference will be made to the route searching processing carriedout according to the route searching part 6 by making use of theavoidance points extracted in this manner while referring to a flowchart of FIG. 12. First of all, the route searching part 6 receives aninput of a destination from a user (step S121), selects from thealgorithm preference degree table 57 a route selection algorithm thatmeets the route selection preference of the user (step S122), andcarries out a route search by using the algorithm thus selected (stepS123). Then, it is determined whether there exists a link that matchesan avoidance point stored in the avoidance point table 9 in a routeobtained as a result of the search (step S124). When there exists anavoidance point on the searched route, an adjustment is performed suchthat the search cost for the link is increased so as to make the linkless prone to be selected (step S125). Thereafter, the route searchprocessing is executed again based on the search cost after having beenthus adjusted. Such processing is executed until there exists noavoidance point on the route obtained as a result of the search, oruntil the same route is searched or obtained even if the search cost isadjusted, but an upper limit value can be set for the frequency ofre-search. Then, the route thus obtained is presented to the user as theroute resulting from the search (step S126).

<Effects of this Embodiment>

According to this embodiment, it is possible not only to use analgorithm that most meets the route selection preference of a user,among route searching algorithms that have been defined beforehand, butalso to perform a route search in such a manner that the roads which theuser tends to avoid are made less prone to be selected. That is, itbecomes possible to perform a route search reflecting thereon the routeselection tendency of the user in a more flexible manner.

REFERENCE SINGS LIST

-   -   3 a travel route accumulation part    -   4 a travel history table    -   5 an algorithm selection part    -   51 a route match rate calculation part    -   55 a match rate table    -   56 an algorithm preference degree calculation part    -   57 an algorithm preference degree table    -   6 a route searching part    -   7 a mismatch point table    -   8 an avoidance point extraction part    -   9 an avoidance point table

1. A route searching apparatus capable of using a plurality of routesearching algorithms, comprising: a travel route accumulation unit thatacquires and accumulates routes which have been traveled; an algorithmselection unit that selects a route searching algorithm to meetpreference of a user based on the travel routes accumulated in saidtravel route accumulation unit; and a route searching unit that performsa route search up to a destination by using the algorithm selected bysaid algorithm selection unit, wherein said algorithm selection unitsearches for a route leading from a starting point to a destinationpoint of each of the travel routes accumulated in said travel routeaccumulation unit by means of said plurality of algorithms, calculates aroute match rate for each algorithm which is a match rate between theroute obtained as a result of the search and an actual travel route,calculates, for each algorithm, a match rate between a route selectiontendency of the user and the algorithm based on the route match rate ofeach route, and selects, as an algorithm to meet the preference of theuser, an algorithm of which match rate with respect to the routeselection tendency of the user is the highest.
 2. The route searchingapparatus as set forth in claim 1, wherein said algorithm selection unitseeks mismatch points that are points at which the route obtained as aresult of the search and the actual travel route branch from each other,performs, when there exists a mismatch point, a new route search fromthe mismatch point onward, and calculates said route match rate bymaking use of this search result, too.
 3. The route searching apparatusas set forth in claim 1, wherein said algorithm selection unit seeksmismatch points that are points at which the route obtained as a resultof the search and the actual travel route branch from each other, andextracts a common point for a plurality of mismatch points obtained froma plurality of search results; and when performing a route search bymeans of said selected algorithms, said route searching unit performsthe route search by making larger the cost for a link matching saidcommon point.
 4. The route searching apparatus as set forth in claim 3,wherein said route searching unit performs the search by using saidselected algorithms, and when there exists a link matching said commonpoint on the searched route, a route search is performed again after thecost of the link is set larger.
 5. A route searching method comprising:a travel route accumulation step to acquire and accumulate routes whichhave been traveled; an algorithm selection step to select a routesearching algorithm to meet preference of a user based on theaccumulated travel routes; and a route searching step to perform a routesearch up to a destination by using the selected algorithm, wherein saidalgorithm selection step comprises: a step to search for a route leadingfrom a starting point to a destination point of each of the travelroutes accumulated in said travel route accumulation step by means of aplurality of algorithms, a step to calculate a route match rate for eachalgorithm which is a match rate between the route obtained as a resultof the search and an actual travel route, a step to calculate, for eachalgorithm, a match rate between a route selection tendency of the userand the algorithm based on the route match rate of each route, and astep to select, as an algorithm to meet the preference of the user, analgorithm of which match rate with respect to the route selectiontendency of the user is the highest.
 6. The route searching method asset forth in claim 5, wherein in said algorithm selection step, mismatchpoints are sought that are points at which the route obtained as aresult of the search and the actual travel route branch from each other,and when there exists a mismatch point, a new route search is performedfrom the mismatch point onward, and said route match rate is calculatedby making use of this search result, too.
 7. The route searching methodas set forth in claim 5, wherein in said algorithm selection step,mismatch points are sought that are points at which the route obtainedas a result of the search and the actual travel route branch from eachother, and a common point for a plurality of mismatch points obtainedfrom a plurality of search results is extracted; and in said routesearching step, when a route search is performed by means of saidselected algorithms, the route search is performed by making larger thecost for a link matching said common point.
 8. The route searchingmethod as set forth in claim 7, wherein in said route searching step,the search is performed by using said selected algorithms, and whenthere exists a link matching said common point on the searched route, aroute search is performed again after the cost of the link is setlarger.
 9. The route searching apparatus as set forth in claim 2,wherein said algorithm selection unit seeks mismatch points that arepoints at which the route obtained as a result of the search and theactual travel route branch from each other, and extracts a common pointfor a plurality of mismatch points obtained from a plurality of searchresults; and when performing a route search by means of said selectedalgorithms, said route searching unit performs the route search bymaking larger the cost for a link matching said common point.
 10. Theroute searching apparatus as set forth in claim 9, wherein said routesearching unit performs the search by using said selected algorithms,and when there exists a link matching said common point on the searchedroute, a route search is performed again after the cost of the link isset larger.
 11. The route searching method as set forth in claim 6,wherein in said algorithm selection step, mismatch points are soughtthat are points at which the route obtained as a result of the searchand the actual travel route branch from each other, and a common pointfor a plurality of mismatch points obtained from a plurality of searchresults is extracted; and in said route searching step, when a routesearch is performed by means of said selected algorithms, the routesearch is performed by making larger the cost for a link matching saidcommon point.
 12. The route searching method as set forth in claim 11,wherein in said route searching step, the search is performed by usingsaid selected algorithms, and when there exists a link matching saidcommon point on the searched route, a route search is performed againafter the cost of the link is set larger.